The Industar-61 52/2.8 was the ffirst manual lens i ever used and i loved the results, but i fear it's one of those frankenstein cameras made out of spare lens parts, because the part that screws to the adapter isn't centered properly and gets stuck often while focusing, which can accidentally unscrew the lens from the camera! It's this type:

A good copy, or mine if i can fix it, could be a really great lens i think, very light also

Boy yours looks decent. They are easy to relube--tutorial on the net.

Yeah, great results from it (and those were my first ever attempts at manual focus!), but it's not a re-lubing issue, i've already done that - like i said, the mount screw-on part isn't centered perfectly, and gets stuck when focusing, unscrewing the lens from the adapter! Your J8 looks like a great copy also.